I proofread quite often and most of the time recognize lots of mistakes, but from time to time I see this usage of the present participle and it always makes me wonder what rules should I apply to see ...

I have been reading up on the correct use of 'which' and 'that' but I am still struggling. I am unsure if 'must be taken regularly' is restrictive or not. Both 'which' and 'that' sound correct to me. ...

I'm confused about two particular examples where "who" is used as a relative pronoun:
Example-1:
...people who I have no idea who are.
...people who I have no idea who they are.
Example-2:
...people ...

In Microsoft Word, the grammar engine in certain situations suggests either placing a comma before which or replacing it with that (and not using a comma).
Does the meaning of a sentence ever change ...

We often omit relative pronouns in restrictive clauses. E.g. "I am flying to a place I love" instead of "I am flying to a place that I love."
It seems ok to omit the which/who in the following. But ...